There are devices and systems that assist safe driving by detecting and feeding back dangerous swaying behavior during driving, the dangerous swaying behavior occurring due to a decrease in concentration on driving. For example, there is a technology which classifies a waveform based on temporal changes in steering angle and lateral displacement into a high-frequency component and a low-frequency component, and determines that there is a low arousal state when a power ratio obtained by dividing the low-frequency component by the high-frequency component is high.
Examples of the related art include Japanese Laid-open Patent Publication No. 2000-185575.
However, the above-described technology may take time to perform waveform signal processing. For example, the above-described technology may need accumulation of displacement amount data for a long time of approximately 50 to 80 seconds to estimate a degree of arousal with high accuracy, and thus take time to perform the signal processing for the waveform classification.